The high threshold for available free addresses in this
shared network. If a cDhcpv4ServerFreeAddressLow event was
generated for this subnet, and the value for available free
addresses has exceeded the value of
cDhcpv4ServerSubnetFreeAddrHighThreshold, then a
cDhcpv4ServerFreeAddressHigh event will be generated. No more
cDhcpv4ServerFreeAddressHigh events will be generated for this
subnet during this execution of the DHCP server until the
value for available free addresses becomes equal to or less
than the value of cDhcpv4ServerSubnetFreeAddrLowThreshold.